One method or technique for conventionally forming threaded fasteners comprises the rolling of a blank member between a pair of thread rolling dies as is disclosed, for example, within U.S. Pat. No. 4,716,751 which issued to Wozniak on Jan. 5, 1988. In accordance with such a conventional manufacturing method or technique for forming threaded fasteners, as illustrated, for example, within FIGS. 1–3, which correspond to FIGS. 1, 1a, and 2 of the aforenoted patent, a blank member 9 is adapted to be interposed between a pair of thread rolling dies 10, 10a wherein, for example, a first one of the thread rolling dies 10 comprises a moving die while the second one of the thread rolling dies 10a comprises a stationary die. Each one of the thread rolling dies 10, 10a comprises a tool steel body 11 having a working face 12, and as best seen in FIGS. 1 and 3, and as described in connection with the thread rolling die 10, the working face 12 is provided with a plurality of die threads 13 which extend from a start end 14 of the thread rolling die 10 toward a finish end 16 of the thread rolling die 10, and which are disposed at a predetermined angle with respect to the axial or longitudinal extent or axis L of the thread rolling die 10 in order to in fact form the threads upon the blank member 9.
As the blank member 9 is rolled between the two thread rolling dies 10, 10a from the start end 14 of the thread rolling die 10 toward the finish end 16 of the thread rolling die 10, the material comprising the blank member 9 is progressively displaced and flows into or between the thread rolling die threads 13 whereby fully formed threads, which mate with or correspond to the thread rolling die threads 13 of the thread rolling dies 10, 10a, are produced upon the blank member 9. More particularly, as can best be appreciated from FIG. 3, each one of the thread rolling die threads 13 comprises a plurality of crest portions 17, which are adapted to penetrate the blank member material during the thread rolling operation so as to effectively and ultimately form the root portions of the threads upon the blank member 9, and a plurality of root portions 19 which are adapted to ultimately form the crest portions of the threads upon the blank member 9 at the completion of the thread rolling operation. Lastly, flank portions 18 of the thread rolling die threads 13 define surfaces along which the blank member material flows during the formation of the crest and root portions of the threads upon the blank member 9, and the flank portions 18 of the thread rolling die threads 13 likewise form corresponding thread flank portions upon the blank member 9. It is further noted that as the rolling process proceeds, the material comprising the blank member continues to be displaced along the flank portions 18 of the thread rolling die threads 13 with the depth of penetration increasing as the rolling process continues until a fully formed thread is produced upon the blank member 9 at the finish ends 16 of the thread rolling dies 10, 10a. 
With reference now being made to FIG. 4, there is disclosed a conventional threaded fastener 100 which is known in the industry as a “hi-low” thread form in view of the fact that the same comprises two different thread leads, that is, a first, primary thread lead 102, and a second, auxiliary thread lead 104 which provides reinforcement characteristics to the threaded fastener 100. The primary and auxiliary thread leads 102, 104 are disposed upon the threaded fastener 100 in such a manner that successive portions of the auxiliary thread lead 104 are interposed between successive portions of the primary thread lead 102 along the axial extent of the threaded fastener 100, and it is particularly noted that the axial distance or pitch, as defined between each set of primary and auxiliary thread leads 102, 104, is denoted by P, while the axial distance or pitch, as defined between, for example, successive primary or successive auxiliary thread leads 102, 102 or 104, 104, is 2P. The root portion of the threaded fastener 100 is disclosed at 106, and it is noted that the crest height of the first, primary thread lead 102, as measured from the root portion 106 of the threaded fastener 100, is adapted to be at least twice the crest height of the second, auxiliary thread lead 104 as similarly measured from the root portion 106 of the threaded fastener 100. One of a pair of thread rolling dies, for forming the primary and auxiliary thread leads 102, 104 upon a fastener blank member 108 in a manner similar to the aforenoted use of thread rolling dies 10, 10a in connection with the formation of the threads upon the fastener blank member 9, is disclosed at 110, and it is seen that in order to ultimately form the primary and auxiliary thread leads 102, 104 upon the fastener blank member 108, the thread rolling die 110 comprises a plurality of primary thread rolling die threads 112, and a plurality of auxiliary thread rolling die threads 114. In a manner corresponding to the alternative disposition of the first, primary thread leads 102 and the second, auxiliary thread leads 104 upon the threaded fastener 100, the plurality of primary thread rolling die threads 112 and the plurality of auxiliary thread rolling die threads 114 are similarly disposed in an alternative manner upon the thread rolling die 110.
More particularly, in connection with each one of the thread rolling die threads 114, it is seen that the crest portion of each auxiliary thread rolling die thread 114 actually comprises a pair of crest portions 114a, 114b, wherein each one of the crest portions 114a, 114b of each auxiliary thread rolling die thread has a lateral or transverse extent of between 0.003–0.010 inches, and wherein further, the crest portions 114a, 114b are laterally or transversely spaced from each other by means of a predetermined distance so as to in fact form each one of the second, auxiliary thread leads 104 therebetween during the thread rolling process. In particular, recalling the fact that the depth of penetration of the thread rolling dies increases as the thread rolling process continues, and appreciating the additional fact that each one of the thread rolling die threads 112, 114 is disposed at a predetermined angle with respect to the longitudinal or axial extent or axis of the thread rolling die 110, then it can be appreciated further that in order to fully form the first, primary thread lead 102 upon the threaded fastener 100, after the second, auxiliary thread lead 104 has been formed so as to have a predetermined depth, a predetermined amount of blank member material 116 must be displaced or moved a predetermined lateral or transverse distance during the thread rolling operation.
It is also conventionally known, however, that, in accordance with thread rolling manufacturing techniques, and the practical limitations inherently associated therewith, a predetermined amount of blank member material can only be displaced a predetermined distance during each rotation or revolution of the blank member along the pair of cooperating thread rolling dies in order to in fact achieve good, reliable, straight threads upon the blank member. Consequently, the greater the distance that the blank member material must be displaced, the greater the number of rotations or revolutions that the blank member must undergo during the thread rolling process until the thread leads are fully formed upon the original blank member. Accordingly, if the blank member must undergo a substantially large number of rotations or revolutions, then the longitudinal or axial length of each thread rolling die must be substantially large which, in turn, requires the use of a substantially large thread rolling machine which renders the manufacture of the threaded fasteners relatively costly.
Since the practical problem in connection with the formation of, for example, the first, primary thread lead 102 upon the fastener blank member 108 resides in, or is a function of, the pitch spacing 2P between successive threads of the first, primary thread lead 102, and therefore the distance through which the blank material must be moved or displaced during the thread rolling process in order to form the successive threads of the first, primary thread lead 102, then one solution to this problem might be to shorten the pitch spacing between successive threads of the first, primary thread lead 102. The shortening of the pitch spacing between successive threads of the first, primary thread lead 102 would, however, increase the number of threads per inch that would be present upon the threaded fastener 100. This alteration in the number of threads per inch, as present upon the threaded fastener 100, however, adversely alters the operational characteristics of the threaded fastener 100, such as, for example, the amount of insertion torque required in connection with the driving of the threaded fastener into a substrate, the amount of time it takes to insert or drive the threaded fastener 100 into the substrate, the pull-out resistance of the threaded fastener 100 with respect to the substrate, and the like.
A need therefore exists in the art for a new and improved threaded fastener, a new and improved thread rolling die for forming the new and improved threaded fastener, and a new and improved method or technique of manufacturing the new and improved threaded fastener whereby the manufacturing process can be readily facilitated in view of the fact that, during the formation of the predetermined number of threads per inch comprising the thread leads of the threaded fastener in accordance with the thread rolling process, the blank member material only needs to effectively be displaced or moved through a smaller lateral or transverse distance in order to complete the formation of the thread leads upon the blank member such that, in turn, the longitudinal or axial length of the thread rolling dies can be substantially shortened so as to, in turn, require the use of a substantially shortened thread rolling machine which renders the manufacture of the threaded fasteners more cost effective.